The present invention relates to an external storage device, a control device, an external storage system, a control method, a program, and a recording medium. Specifically, the present invention relates to an external storage device, a control device, an external storage system, a control method, a program, and a recording medium, which perform failure recovery control.
In a mode in which an external storage device is connected to a plurality of hubs, a networking model has been proposed (Thomas Clark, “Designing Storage Area Networks: A Practical Reference for Implementing Fibre Channel SANs,” Pearson Education, 09/1999). In the networking model, when a failure occurs in communications between the external storage device and one of the hubs, a host computer communicates with a disk device inside the external storage device through the other hubs.
However, if the external storage device is enabled to communicate through a plurality of hubs, respective usage rates of data streams are lowered. As a result, a ratio of costs to traffic is increased.